Apple's iTunes U is growing at an unprecedented rate, the company announced on Tuesday.

According to Apple, its online store's educational section has hit more than 300 million downloads. Currently, more than 800 universities have iTunes U sites, and almost half of those schools, including Harvard University and Oxford University, offer content through the iTunes Store. Apple said that users can now access "over 350,000 audio and video files" through iTunes U.

iTunes U, which launched in 2007, has been seeing steady, but somewhat subdued growth since its launch. That's why the company's latest announcement of 300 million downloads is all the more staggering. In December, Apple announced that it had recorded 100 million downloads on content from 175 organizations.

Part of the reason for that immense growth could be the recent addition of content from universities in China, Hong Kong, Japan, Mexico, and Singapore. Plus, since all the content is free to download, the barriers to entry are quite low.